Update to ZDoom r2073:

- added initial support for a GAMEINFO lump in PWADs. When the game is started
  all files loaded with '-file' are scanned for this lump. This lump is read
  before any WAD initialization takes place, in particular the IWAD is not yet
  loaded at this time. This allows PWADs the option to specify an IWAD they 
  want to run with and optionally autoload external resource WADs.
- Fixed a few places where FixPathSeperator was called with a locked FString buffer.
  It's better to use the FString version of this function instead.
- replaced wadlist_t with an array of FStrings and added a list parameter to
  everything that eventually calls D_AddFile. Also create the list of files
  loaded on the command line separately to allow further checks on them.
- fixed: The node builder did not check if all segs could be split properly.
  Also removed some fudging that tried to work around this case but produced
  a broken BSP tree on other maps.
- Added Blzut3's Solaris patch.
- Fixed: Heretic's Weredragon (Beast) should not have a melee state.

SBARINFO update:
- Reorganized the SBarInfo code.
- Added interpolate(<speed>) flag to drawnumber, drawbar, and drawgem.  The old
  way of interpolating the health and armor is depreciated.
- Added: armortype to drawswitchableimage loosely based on Gez's submission.
- As an extension to the previous you can now use comparison operators on
  inventory items and armortype in drawswitchableimage.


git-svn-id: http://mancubus.net/svn/hosted/gzdoom/trunk@698 b0f79afe-0144-0410-b225-9a4edf0717df

src/r_bsp.cpp

@@ -1026,6 +1026,7 @@ void R_Subsector (subsector_t *sub)
 #endif
 
 	frontsector = sub->sector;
+	if (sub->sector == NULL) return;
 	frontsector->MoreFlags |= SECF_DRAWN;
 	count = sub->numlines;
 	line = &segs[sub->firstline];